Those who didn't make the field for the first debate were former technology executive Carly Fiorina, the GOP's only female presidential candidate; former Texas Governor Rick Perry; Louisiana Governor Bobby Jindal; South Carolina Senator Lindsey Graham; former Pennsylvania Senator Rick Santorum; former New York Governor George Pataki; and former Virginia Governor Jim Gilmore.

Thursday's event will be the first of six party-sanctioned debates before primary voting begins in February.

Trump has taken the Republican race by storm, drawing big crowds with his blunt rhetoric and willingness to lash out at his rivals.

Perry, 65, one of several Republicans who has had trouble gaining traction in the polls largely because of Trump’s rise, said it is time to “stanch the flow” of illegal immigrants.

Attack or ignore?

The Cleveland debate, held at Quicken Loans Arena, will be the first time the Republican contenders gather on stage in front of a national television audience.

Many people will be watching to see if Trump, 69, continues to demonstrate his trademark aggressiveness in dealing with his rivals.

He has described some of them as “dummies,” “idiots” and “not very smart.” The question is, will Trump’s rivals go on the attack or try to ignore him?

Trump is ahead in the polls largely because conservatives appear drawn to his blunt talk.

“What’s happening is there is a movement going on folks, you know, there is a movement going on and it is a very strong movement. We want to take back this country. We have to take it back. We have to take it back,” Trump said at a recent rally in Iowa.

So far, the secret to Trump’s success seems to be that he has touched a nerve with frustrated and angry Republican voters like no one else.

“There is just enormous dissatisfaction with Washington. People are much more satisfied with their state governors and with their local authorities. But there is a lot of dissatisfaction with Washington,” said Karlyn Bowman, who monitors public opinion at the American Enterprise Institute.

Condemns attacks

Bush, 62, has condemned Trump’s attacks on immigrants and some of his Republican rivals.

“And the way you win is that you draw people towards your cause. You don’t push people away. You don’t run a campaign of grievance where you are pushing people aside where your form of conservative thought it slightly better than another person’s conservative thought," Bush said.

The number of debates will give candidates a chance to gain standing — or lose it.

“There will be enough debates that one bad debate won’t hurt anybody,” said John Fortier of the Bipartisan Policy Center. “But somebody who shows consistent performance through the debates may rise up into the top tier, or somebody may underperform.”

From the beginning it was assumed former Secretary of State Hillary Clinton, 67, had a lock on the Democratic Party’s presidential nomination.

Then along came Vermont Senator Bernie Sanders, 73, who drew big crowds with a promise to focus on income inequality.

In recent weeks, some Democrats have expressed concern that Clinton’s favorability ratings have begun to dip as voters express doubts about her trustworthiness.

Now comes word that Vice President Joe Biden might be interested in running for president after all.

Biden has been out of the limelight of late, following the death of his son Beau Biden in May. New York Times columnist Maureen Dowd reported Beau Biden had urged his father to run in 2016 shortly before his death.

There has been no official comment from the vice president, and Politico reports sources close to Biden say he is not ready to make a decision.

White House spokesman Josh Earnest told reporters the vice president has said a presidential campaign is “possible” and that he would make a decision “by the end of summer.”

A decision by Biden to join the race could be reassuring to some Democrats who are worried about Clinton’s weakening favorability ratings, even as she retains a sizable lead in the Democratic race against Sanders and three others.

Jim Malone has served as VOA’s National correspondent covering U.S. elections and politics since 1995. Prior to that he was a VOA congressional correspondent and served as VOA’s East Africa Correspondent from 1986 to 1990. Jim began his VOA career with the English to Africa Service in 1983.